Synchronization signal detection is important for cell search in mobile communication. Generally, a synchronization signal such as Primary Synchronization Signal (PPS) or Primary Synchronization Signal (SSS) is carried by OFDM symbols in a radio signal. In Long Term Evolution (LTE) system, a synchronization signal is transmitted in 6 subframes and occupies one OFDM symbol in each subframe. A traditional approach of detecting such synchronization signal is to filter the radio signal using a matched filter that spans the whole time duration spanned by a synchronization signal to determine if a synchronization signal exists.
Internet-of-Things (IoT) is the vision of virtually all objects being connected to the internet, where the objects can be anything from simple sensors to sophisticated machinery such as vehicles. The Third Generation Partnership Project (3GPP) is currently specifying a new kind of radio access technology (RAT) with strong commonalities with LTE but operating over a narrower bandwidth. The new RAT is referred to as Narrow-Band IoT (NB-IoT).
In NB-IoT system, different cyclic prefix configurations of OFDM symbols such as Normal Cyclic Prefix (NCP) and Extended Cyclic Prefix (ECP) configurations are employed. Synchronization signal is designed special for NB-IoT system, which is different from that for normal LTE system.
There is no solution in the art to detect such synchronization signal. If detect it in the same fashion as for regular LTE, such as by using a matched filter that spans the whole time duration spanned by the synchronization signal, there will be a need to perform two kinds of matched filtering operations—one for NCP configuration and one for ECP configuration, because the synchronization signal is spread out on multiple OFDM symbols at different distances depending on cyclic prefix configuration.
It is desirable to provide an efficient solution to detect such synchronization signal.